A Trial of Two Family-based Childhood Obesity Treatment Programs: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Trial of Two Family-based Childhood Obesity Treatment Programs (NCT03245775), a randomized na study. The primary outcome is Change From Baseline in Child Body Mass Index (BMI) Z-score at 6 Months.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group behavioral trial comparing iChoose with Family Connections. The registry record identifies allocation as randomized and masking as none. It lists the phase as not applicable. The study is marked completed, with enrollment of 267. The recorded start date is 2017-06-01 and the primary completion date is 2019-11-30. The sponsor was the University of Virginia.

The interventions differed in who received the program and in their activities. iChoose delivered the intervention to parents and children and included structured physical activity sessions. Family Connections delivered the intervention to parents, promoted physical activity, and did not include structured exercise sessions. These are descriptions of the intended program components in the registry record; they do not establish how consistently participants attended or how fully the programs were delivered.

The posted primary endpoint is child BMI z-score change from baseline to 6 months. The primary outcome record reports 70 children in the iChoose-Child arm and 69 in the Family Connections-Child arm. These endpoint counts are distinct from the overall enrollment figure. The record also lists parent arms in the adverse-event data, with 66 parents in the iChoose group and 62 in the Family Connections group at risk for the reported event categories.

The trial summary describes other aims, including reach, fidelity, implementation costs, community capacity, family eating and physical activity, parental weight, adherence, and potential dose-response relationships. It also describes relative effectiveness at 3, 6, and 12 months post baseline. The posted primary outcome is the 6-month child BMI z-score change; results for those additional aims are not reported in the registry record beyond the listed secondary outcomes.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Child Body Mass Index (BMI) Z-score at 6 Months, measured over Baseline and 6-months.

The primary endpoint is change from baseline in child BMI z-score at 6 months, measured in z-scores. The registry describes a BMI z-score as a standardized measure based on a child’s height, weight, age, and gender. A score of 0 represents an average BMI for those characteristics; positive scores are above the norm and negative scores are below it. The endpoint is a change score: the 6-month z-score minus the baseline z-score.

The direction matters. As defined in the registry record, a negative change indicates a reduction in BMI z-score status and is described as a positive finding. A positive change indicates an increase in the score. The mean change summarizes the average change among the children contributing to each arm’s reported result; it does not describe every child’s individual trajectory.

A standardized measure allows the outcome to be interpreted relative to a reference distribution rather than as raw BMI alone. It is the outcome chosen to address the trial’s question about child BMI status. The endpoint does not directly measure reach, attendance, physical activity, family eating, parental weight, or the implementation of the programs. Although the trial summary refers to assessments at multiple follow-up times, the posted primary outcome result is for the change from baseline to 6 months.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The trial used randomized allocation and a parallel-group design, according to the registry record. In a randomized trial, the allocation process is intended to make the groups comparable on average with respect to measured and unmeasured characteristics. Randomization does not guarantee that every realized group is identical, and its value for estimating a treatment contrast depends on an analysis that preserves the randomized comparison. The registry identifies the allocation as randomized but does not report the sequence-generation method, allocation concealment, or detailed analysis procedures.

What does the mean change summarize?

The primary endpoint is continuous: each child’s change in BMI z-score can take a range of numerical values. The registry reports the mean for each arm. A mean gives the arithmetic center of the observed changes, but it can be influenced by unusually high or low values and does not show the spread or shape of individual observations. No standard deviation or other measure of within-arm spread is listed for the primary outcome. The posted confidence intervals describe uncertainty around the reported mean, not the variation among individual children.

Change scores compare a follow-up measure with baseline for the same outcome. In this record, the change is defined as the 6-month BMI z-score minus the baseline BMI z-score. The endpoint therefore expresses movement in the standardized score rather than the 6-month score alone. The registry describes negative change as a reduction in BMI z-score status. It does not report whether the statistical analysis adjusted for baseline values or used a different model alongside the change-score summary.

How should the confidence intervals be read?

A confidence interval gives a range of values generated by a statistical procedure to represent uncertainty about an estimate. In general, narrower intervals indicate greater precision under the assumptions of the method, while wider intervals indicate less precision. The intervals posted for the two arms both extend across zero. That observation describes each arm’s mean change separately. It does not test the difference between arms. To answer a comparative question directly, an analysis would ordinarily estimate the between-arm contrast and its uncertainty, using a method appropriate to the design and outcome. Such a contrast is not reported in the registry record.

Confidence intervals depend on assumptions, including how observations are treated and how uncertainty is estimated. The registry lists a mean and 95% confidence interval but does not identify the model, variance estimator, covariates, or other details used to obtain them. Those methodological details are not reported in the registry record, so the intervals cannot be independently attributed to a particular analysis method from the record alone.

Why does the design matter?

The parallel design assigns participants to one of the intervention groups for the comparison described in the record. The programs differ in structure and intended recipients, so the randomized comparison concerns the assigned program packages rather than the isolated contribution of any single component. The record says masking was none. It does not describe whether outcome assessors were masked, how BMI measurements were collected, or whether the people analyzing the results knew assignment. Those details are not reported in the registry record.

The trial summary names several additional aims, including implementation, family behaviors, parental weight, adherence, and potential dose-response relationships. Each aim would require appropriate outcome definitions and analysis methods. The registry lists three secondary outcomes: parent BMI change at 6 months, children’s Pediatric Quality of Life Inventory score change at 6 months, and parents’ Healthy Days Core Module change at 6 months. The record does not give results or analysis details for those outcomes in the information.

What can planning illustrations tell a reader?

Sample-size planning is distinct from an observed trial result. The planning assumptions described for the illustrations use a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. Such calculations illustrate sample sizes under chosen assumptions. They are not observed power, and they do not show the probability that the trial produced a statistically significant result. The registry record does not report the trial’s own sample-size justification or design assumptions, and no planning sample-size figures are stated in the record.

Because a direct between-arm effect estimate is not posted for this continuous endpoint, the arm-specific means should not be mistaken for a demonstrated comparative effect. The registry marks the two-arm continuous comparison as having values that are missing or not estimable. No recalculated comparison is available in the posted results. The record does not identify a statistical analysis plan, prespecified model, adjustment strategy, or interim analysis procedure. Those items are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes in addition to the primary endpoint. When a study evaluates multiple outcomes or time points, the chance of a chance finding across the set can differ from the chance associated with a single test. Statistical methods can address multiplicity, but the appropriate approach depends on which comparisons were prespecified and how they were intended to support conclusions. The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or a detailed plan for interpreting multiple tests. It also does not report analyses for the listed secondary outcomes in the information recorded.

The trial summary refers to effectiveness at 3, 6, and 12 months post baseline, while the posted primary outcome is the 6-month change. The record does not give a multiplicity plan for assessments across time, or clarify how the primary outcome timing relates to any planned repeated-measures analysis. These details are not reported in the registry record.

Missing-data handling can affect estimates when outcome measurements are unavailable. Statistical approaches may rely on different assumptions about why data are missing and how the observed data relate to the missing values. The registry record does not describe missingness by arm, reasons for missing measurements, imputation, sensitivity analyses, or another missing-data method. It also does not identify the analysis population, such as whether the primary analysis followed randomized assignment or included only participants with observed follow-up measurements. Those details are not reported in the registry record.

The overall enrollment is 267, while the child primary outcome groups report 70 and 69 participants. The record does not account for all enrolled participants in relation to the primary endpoint. Without information about participant flow and analysis populations, the endpoint counts alone cannot explain who contributed to the estimates or why other enrolled participants are not represented in those arm summaries.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists four groups: iChoose-Parent, iChoose-Child, Family Connections-Child, and Family Connections-Parent. The numbers at risk are 66, 70, 69, and 62, respectively. For each group, the record reports zero participants affected by serious adverse events and zero affected by other adverse events. It also reports zero deaths in each group. No serious adverse-event terms are listed.

These figures describe what was recorded in the registry for the stated groups and event categories. A count of zero means that no affected participants were reported in that category; it does not demonstrate that the true risk is zero. Interpretation depends on how events were defined, collected, followed, and attributed, and those details are not reported in the registry record. The record also does not provide event-level descriptions or information about the duration of safety monitoring.

The parent and child groups are reported separately. They should not be treated as interchangeable populations, and their counts should not be combined to create a new total. The registry’s safety figures do not establish a comparative safety effect between the programs, particularly without an analysis of event rates, follow-up, and uncertainty. They are descriptive counts in the posted record, not medical advice or a guarantee about an individual participant’s risk.

12. What the Result Does, and Does Not, Mean

The posted results establish that the registry reports arm-specific mean changes in child BMI z-score at 6 months, together with 95% confidence intervals. The iChoose-Child mean change is 0.03, and the Family Connections-Child mean change is 0.0. Both confidence intervals include zero. Given the endpoint’s stated direction, the point estimates are close to no change, while the intervals also encompass negative and positive mean changes.

Those summaries do not establish that one program is better than the other. A comparative conclusion requires a direct estimate of the difference between randomized groups, with its uncertainty and an appropriate analysis. That direct comparison is not reported in the registry record. Nor do the arm-specific estimates establish equivalence: the record does not report an equivalence margin or a corresponding analysis.

The results also do not show what would have happened without either program. Both groups received a behavioral intervention, and the registry does not list a no-intervention control arm. The data therefore do not estimate either program’s effect relative to no treatment or usual care. They do not identify which program component, if any, accounts for a change, because the programs differ in more than one described feature.

The primary endpoint is child BMI z-score change, not a comprehensive measure of health, participation, family behavior, or community implementation. The trial summary names broader goals, but their results are not reported in the registry record. The primary outcome counts also do not explain the status of every enrolled participant. Missing-data methods and analysis populations are not reported, which limits assessment of how the estimates relate to the full enrolled group.

Accordingly, the most defensible reading is descriptive and bounded: the record gives mean 6-month changes within each child arm, but does not provide the direct analysis needed to resolve the relative-effectiveness question. The results should not be extended beyond the endpoint, time point, populations, and comparisons actually recorded.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction between reporting outcomes by arm and reporting a randomized treatment contrast. The primary question concerns the relative effectiveness of two programs, but the posted child outcome results give a mean change and confidence interval separately for each arm. Those summaries can describe the observed change within each group, yet they do not directly quantify the difference attributable to assignment between the programs.

The distinction matters because uncertainty around two separate means is not the same as uncertainty around their difference. A comparative analysis uses the trial’s randomized structure to estimate a between-group effect and its precision. Without that direct estimate, readers should avoid inferring a comparative conclusion from point estimates alone or from visual inspection of the two intervals. The registry record does not provide the contrast or its statistical test.

The record also makes clear that a trial can have broader aims than the results posted for a particular outcome. The summary mentions reach, fidelity, implementation costs, community capacity, family behaviors, parental weight, adherence, and dose-response relationships. The listed primary result addresses only child BMI z-score change at 6 months. Keeping the outcome and time point explicit prevents an estimate from being interpreted as evidence about all aspects of a complex intervention.

Finally, the difference between overall enrollment and the child outcome counts highlights why participant flow and analysis-population definitions are important for interpretation. The record does not explain that difference or describe its missing-data approach. Reporting those details alongside a direct contrast would help readers assess the precision and scope of the findings. The posted information supports a careful account of what was measured, while leaving important comparative and analytic questions unresolved.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several trial-specific limitations of interpretation follow from what the registry record reports and does not report. The primary outcome is available as separate arm means and confidence intervals, but the direct between-arm comparison is not reported. This leaves the central relative-effectiveness question unanswered by the posted primary result. The record also marks the two-arm continuous comparison as having values that are missing or not estimable.

The primary endpoint is limited to change in child BMI z-score from baseline to 6 months. Although the trial summary refers to assessments at 3, 6, and 12 months, results for the other time points are not reported in the registry record. The record also lists secondary outcomes for parent BMI, children’s quality of life, and parents’ healthy days, but does not report results for them in the information.

The registry does not describe the analysis model, baseline adjustment, participant flow, analysis populations, missing-data methods, multiplicity plan, or sensitivity analyses. These omissions limit evaluation of how the estimates were calculated, how missing measurements may have affected them, and how the several outcomes and follow-up times were handled. The overall enrollment and the child outcome counts are both reported, but the record does not explain the relationship between them.

The interventions were different packages: iChoose involved parents and children and included structured activity sessions, whereas Family Connections involved parents and promoted activity without structured exercise sessions. The comparison therefore cannot isolate the contribution of any one program component. The registry also identifies masking as none, without specifying whether outcome assessors or analysts were masked. Details about measurement procedures and intervention adherence are not reported in the registry record.

These limitations do not change the values recorded for the arm-specific outcome or adverse-event counts. They constrain how far those values can support conclusions about comparative effectiveness, implementation, or safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Trial of Two Family-based Childhood Obesity Treatment Programs — NCT03245775.
• Registry record last updated 2024-06-28; status last verified 2024-01.
• Results first posted 2024-06-28.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03245775 is a completed randomized, parallel-group trial sponsored by the University of Virginia. It enrolled 267 participants and compared two behavioral programs for childhood obesity in a medically underserved region: iChoose and Family Connections. The registry lists no masking and identifies the phase as not applicable.

The posted primary outcome is child BMI z-score change from baseline to 6 months. The iChoose-Child arm reports a mean change of 0.03, with a 95% confidence interval from -0.13 to 0.19; the Family Connections-Child arm reports 0.0, with a 95% confidence interval from -0.16 to 0.16. A direct between-arm estimate is not reported in the registry record.

The record lists three secondary outcomes and reports zero serious adverse events, zero other adverse events, and zero deaths in each of the four parent and child groups. Analysis methods, missing-data handling, analysis populations, and results for the secondary outcomes are not reported in the registry record.